Sharpening device



F. E. BROBERG SHARPENING DEVICE Filed Oct. 30, 1944 INVENTOR ATTORNEYS Patented Oct. 3 0, 1945 UNITED STATES PATENT OFFICE SHARPENIN G DEVICE Fred E. Broberg, Racine, Wis. Application October 30, 1944, Serial No. 561,051 2 claims. (c1. 51-116) My invention refers to sharpening devices of the rotary type such as disclosed in my prior patents, Numbers 2,019,471 and 2,264,065 issued respectively to me October 29, 1935, and November 25, 1941.

The primary object .of my present invention is to provide angularly disposed abrasive sh'oes, such as disclosed in my previous patents, with means for adjusting the angilar position of said shoes, with reference to the point of grinding, whereby the bevel of a knife blade at the cutting edge can be varied.

Another object of my invention is to provide obliquely disposed shafts for the abrasive shoes connected at their inner ends by a common pivot or center, about which' the shafts and abrasive shoes are adjusted as to angle, whereby practically no change of height, at the grinding point or front end, is developed. In other words, the shafts are mounted on a common axis, whereby the height of th'e shoes, at their front or grinding point, are not varied.

A further object is to provide a two part guide for a knife blade which is to be ground, whereby said blade, under certain conditions, can be sharpened directly up to the hilt of the handle, and to provide a manually controlled lever mechanism associated with the outer ends of the obliquely disposed shafts, whereby they may be selectively raised or lowered to change the angle of same and be locked in such changed positions.

Another object of my invention is to provide a fixed anchor point carried by the casing upon which the grinder shafts are pivoted, and to provide pairs of grinding shoes composed of abrasive material with yielding means at the ends of carrying arms, whereby the grinding elements or shoes, when engaging the surface of a cutting blade, may be slightly cushioned as to pressure.

A still further object of my invention is to provide a simple and economical means for anch'oring the cushioned grinding shoes whereby they may be readily removed for dressing or renewal purposes.

With the above and other minor objects in view, the invention consists in certain peculiarities of construction and combination of parts as will hereinafter be fully set forth with reference to the accompanying drawing.

In the drawing:

Figure 1 represents a side elevation of a rotary Sharpener or grinder embodying the features of my invention, the same being partly broken away and partly in section to more clearly illustrate structural features.

Figure 2 is an enlarged cross sectional view of same, the section being indicated by line 2-2 of Figure 1.

Figure 3 is a fragmentary magnified plan view,

the same being partly in section as indicated by line 3-3 of Figure 1 and illustrating the fixed pivot of companion pivotal connected grinder shafts.

Figure 4 is a detailed sectional view showing pivoted means for varying the angle of the grinder shafts, as indicated by line 4 4 of Figure 1.

Figure V5 is a fragmentary faced view of the feed end of the machine illustrating the blade guide with the guide handle in section, as indicated generally by line 5-5 of Figure 1.

Figure 6 is a fragmentary detailed view of the casing side Wall, illustrating the casing guide slot means'for permitting adjustment of one of the grinder shafts.

Figure 7 is a detailed plan view illustrating one of the abrasive shoes and associated arm which is yielding, connected at ends of the shoe, parts being broken away and in section.

Referring .by characters to the drawing A indicates a casing provided with a removable cover cap B, which cap is partly circular in form and provided with a central slot C formed by parallel connected Walls, the bottom D,'of which serves as a guard for the blade of a knife to be sharpened, as indicated in dotted lines El.

The casing has secured thereto a bracket I, as best shown in Figures l and 3 of the drawing, and the end bracket terminates in a stud 2, upon which is pivoted the inner end of a pair of grinder shafts 3, which shafts, as shown, are at angles relative to each other or obliquely disposed, and the outer ends of said shafts are guided in vertical disposed slots 4 of the casing, whereby said shafts are adjusted to vary the relative angle thereof.

As best shown in Figures 1 and 2 of the drawing, the free ends of the shafts are supported by straps 5, the lower ends of which are pivotally connected to arms of a yoke or bell crank lever 6, whichiever in turn is pivoted to the walls of the casing by studs E.

The yoke is formed with a hollow centrally positioned arm 1 having mounted therein a spring controlled plunger stem 8, which stem extends through a vertically positioned slot 9, of the casing. The slot walls are formed in a series of companion circular pockets 9', which pockets are adapted to selectively engage the conical hub I 0 of a button I0.

By this link connection between the button and grinder shafts, the shafts may be selectively raised or lowered to vary the angle thereof and to lock the parts in their adjusted position, due to the engagement of the conical hub I and the wall pockets 9 of the slot, which action is under manual control.

Rotatably mounted upon each of the shafts 3, are spider hubs II, carrying oppositely disposed radial spokes I2, it being understood that the spokes of one spider in assemblage are positioned at a right angle to the spokes of the opposite spider.

As best shown in Figures 1 and 7 of the drawing, the spokes I2 terminate with arms I3 havf ing end apertures I3 for the reception of headed studs I4, which are secured tc segment shaped abrasive shoes I5, the ends of which, as is best illustrated in Figure 7 of the drawing, are slightly ared. vThe abrasive shoes are removably anchored to the spoke arms by the studs I4 and between the face of the arms and abrasive shoe is a rubber washer I6 which serves as a cushion and permits lslight yield of the shoes at both ends.

The shoes are fastened to the arms YI3 by a leaf spring I'I, having a key hole slot vI8 in each end thereof. The slots receive the studs I4 and the outer face of the spring engaging the shouldered heads of the studs I4 Awhen the spring is slid in one direction to lock the shoes in position. To release the studs I4, the spring is shifted longitudinally in the opposite direction until the studs register with the enlarged ends of the slots, at which time the spring I'I can be lifted off the studs. The arms I3 at the leading ends thereof are provided with recesses into which are adapted to snap the 'resilient inturned forward ends I'I' of the springs I'I. This creates a less tension on the springs Vat the leading ends thereof. Consequently, the rear ends of the shoes are held in place vby a greater tension than at the front, which gives the pads the desired wiping action on 'knife being sharpened at the rear ends of said shoes.

As lshown in my previous patent, the rotary spiders are driven by belts 'F from a suitable motor, indicated in dotted lines, it lbeing noted in this instance that the hubs II, which form the ydriving pulleys for the abrasive elements, are circular in form 'without grooves for the belt, whereby sufficient play of the belt is permitted to accommodate variation inthe angular adjustment of said hubs.

The fro-nt ends of the hubs carry'toothed wheels f8, with their lower portions intermeshed vupon a xvertical `line intersecting the center anchorage point of said shafts,hence,whi1e these teeth gears serve yto lsynchronize the independently driven abrasivefeature elements, adjustment relative Yto the angle of the 'shafts will not interfere with the proper tooth mesh or tend to bind with reference to the teeth of the wheels. Y

As indicated in dotted lines by character E, the Sharpener has inserted therein a knife and when this blade is slowly moved back and forth, it will be effectively ground as the wiping abrasive shoes contact with the cutting edge of the blade at the point indicated by the black dot 0. In the movement back and forth of the blade, it is `guided in the throat of a V-.shaped slot I9, formed Aalso guided by a grooved roll 2l of a guide block 22, which guide block is pivoted at its lower end 23 in the walls of a casing slot and the end 23 is formed with a rectangular head 23' which engages the lower portion of the plate spring 20. Said plate spring in addition to serving as a guide under `certain conditions also serves as a spring element to lock the guide block in its upper functional position as shown in Figure l or in its shifted position as indicated in dotted lines in said iigure.

The purpose of this shiftable guide block, carrying the wheel 23, is to accommodate the offset hilts of knife handles which may have shields thereon, which are known to the .trade as the French type, and in sharpening this type of knife, it is desirable to grind the blade as close to the intersection point of the hilt and blade as possible, hence in the last mentioned type of knife the guide 4block 22 is swung downwardly, in vorder that the hilt may have more clearance and can thus be moved inwardly until it contacts with'the casing walls or thin spring plate 2D.

I claim:

l. A blade Sharpener, comprising a companion pair of spaced angularly disposed fixed `shafts having their inner axis lines intersecting, rotary spiders mounted upon the shafts, abrasive shoes carried bythe spiders, a fixed pin in pivotal union with the inner ends of vthe shafts and intermeshed gear wheels carried .by the spiders, in-

dependent driving means connecting the aforesaid spiders, and `means for manually adjusting `the -outer ends ofthe shafts, whereby the angu- 

